Standing just behind the Hôtel de Ville, Saint-Gervais is one of the oldest parishes in Paris, with origins reaching back to the sixth century. The current building mixes Flamboyant Gothic interiors with a striking Classical facade added in the early 1600s — supposedly the first in Paris. Inside, the soaring vaulted nave feels quietly powerful, and the church is renowned for its organ, one of the finest in the city, with a tradition of distinguished organists stretching back centuries. A monastic community still holds daily sung services here, so you may walk into live chant. Far fewer tourists than Notre-Dame, far more atmosphere.